Image scanning apparatus and method implemented in the same

Abstract

An image scanning apparatus, comprising: a scanning device; a reference member; a correction unit; a controller; and a storage device, the scanning device comprising light receiving elements and a lens array, wherein the controller executes: a preparation process and an executive process, the preparation process comprising: a white reference data obtaining process to obtain white reference data by scanning a white reference original; and a white storing process to obtain white basic data by averaging the white reference data of a particular number of adjoining light receiving elements, wherein the executive process comprises: a reference member data obtaining process to obtain reference member data by scanning the reference member; a lens fluctuation calculation process to calculate fluctuation data of the correction data based on the reference member data; and a correction data generation process to generate the correction data by adding the fluctuation data to the white basic data.

What is claimed is: 
     
       1. An image scanning apparatus, comprising:
 a scanning device configured to scan an original sheet; 
 a reference member disposed to face the scanning device; 
 a correction unit configured to execute shading correction for image data obtained by the scanning device based on correction data; 
 a controller; and 
 a storage device, 
 the scanning device comprising:
 a light source; 
 a plurality of light receiving elements arranged in one line; and 
 a lens array having a plurality of lenses, the lens array being configured to converge light emitted by the light source onto the plurality of light receiving elements; 
 
 wherein the controller is configured to execute: 
 a preparation process; and 
 an executive process to be executed after execution of the preparation process, 
 wherein the preparation process comprises: 
 a white reference data obtaining process in which the controller obtains white reference data for each of the plurality of light receiving elements in the one line by causing the scanning device to scan a white reference original sheet; and 
 a white storing process in which the controller obtains white basic data by averaging, for each of the plurality of light receiving elements in the one line, the white reference data of a particular number of successively adjoining elements of the plurality of light receiving elements and stores the white basic data in the storage device, 
 wherein an interval spaced by the particular number of elements corresponds to an interval of the plurality of lenses of the lens array, 
 wherein the executive process comprises: 
 a reference member data obtaining process in which the controller obtains reference member data for each of the plurality of light receiving elements in the one line by causing the scanning device to scan the reference member; 
 a lens fluctuation calculation process in which the controller calculates, for each of the plurality of light receiving elements in the one line, fluctuation data of the correction data based on the reference member data; and 
 a correction data generation process in which the controller generates, for each of the plurality of light receiving elements in the one line, the correction data by adding the fluctuation data to the white basic data. 
 
     
     
       2. The image scanning apparatus according to  claim 1 ,
 wherein the preparation process further comprises a white average calculation process in which the controller calculates a white average by averaging the white reference data of all of the plurality of light receiving elements in the one line, 
 wherein the lens fluctuation calculation process comprises: 
 a reference average calculation process in which the controller calculates a reference average by averaging the reference member data of all of the plurality of light receiving elements in the one line; 
 a reference basic calculation process in which the controller obtains reference basic data by averaging, for each of the plurality of light receiving elements in the one line, the reference member data of the particular number of successively adjoining elements of the plurality of light receiving elements; and 
 a fluctuation data calculation process in which the controller obtains, for each of the plurality of light receiving elements in the one line, the fluctuation data by calculating reference fluctuation data while subtracting the reference basic data from the reference member data, by multiplying the reference fluctuation data by the white average, and by dividing a multiplication result by the reference average. 
 
     
     
       3. The image scanning apparatus according to  claim 2 ,
 wherein: 
 the plurality of light receiving elements is an even number of light receiving elements; 
 in the reference basic calculation process, for each of top side light receiving elements arranged from a top pixel position to a central position in an arrangement region of the plurality of light receiving elements in the one line, the controller calculates the reference basic data by averaging the reference member data of the particular number of successively adjoining elements which successively adjoin from each of the top side light receiving elements toward a last pixel side; and 
 in the reference basic calculation process, for each of last side light receiving elements arranged from the central position to a last pixel position in the arrangement region of the plurality of light receiving elements in the one line, the controller calculates the reference basic data by averaging the reference member data of the particular number of successively adjoining elements which successively adjoin from each of the last side light receiving elements toward a top pixel side. 
 
     
     
       4. The image scanning apparatus according to  claim 3 ,
 wherein: 
 in the white storing process, for each of top side light receiving elements, the controller calculates the white basic data by averaging the white reference data of the particular number of successively adjoining elements which successively adjoin from each of the top side light receiving elements toward the last pixel side; and 
 in the white storing process, for each of last side light receiving elements, the controller calculates the white basic data by averaging the white reference data of the particular number of successively adjoining elements which successively adjoin from each of the last side light receiving elements toward the top pixel side. 
 
     
     
       5. The image scanning apparatus according to  claim 2 ,
 wherein in the reference basic calculation process, the controller divides the plurality of light receiving elements into a plurality of first groups while assigning, sequentially from a top light receiving element, the plurality of light receiving elements to the plurality of first groups in a unit of the particular number of successively adjoining elements, and averages, for each of the plurality of first groups, the reference member data of the particular number of successively adjoining elements assigned to each of the plurality of first groups so as to obtain the reference basic data. 
 
     
     
       6. The image scanning apparatus according to  claim 5 ,
 wherein, regarding a particular one of the plurality of first groups including a last light receiving element, when a number of light receiving elements in the particular one of the plurality of light receiving elements is less that the particular number, the particular number of successively adjoining elements which successively adjoin from the last light receiving element toward the top light receiving element are assigned to the particular one of the plurality of first groups. 
 
     
     
       7. The image scanning apparatus according to  claim 5 ,
 wherein in the white storing process, the controller divides the plurality of light receiving elements into a plurality of second groups while assigning, sequentially from a top light receiving element, the plurality of light receiving elements to the plurality of second groups in a unit of the particular number of successively adjoining elements, and averages, for each of the plurality of second groups, the whit reference data of the particular number of successively adjoining elements assigned to each of the plurality of second groups so as to obtain the white basic data. 
 
     
     
       8. The image scanning apparatus according to  claim 7 ,
 wherein, regarding a particular one of the plurality of second groups including a last light receiving element, when a number of light receiving elements in the particular one of the plurality of light receiving elements is less that the particular number, the particular number of successively adjoining elements which successively adjoin from the last light receiving element toward the top light receiving element are assigned to the particular one of the plurality of second groups. 
 
     
     
       9. A method implemented in an image scanner, the image scanner comprising:
 a light source; 
 a sensor array including a plurality of optical elements arranged in one line; and 
 a lens array having a plurality of lenses, each lens being configured to converge light from the light source onto a particular number of adjoining optical elements; 
 a reference member; 
 a correction circuit configured to execute shading correction using correction data, a controller; and 
 a storage device, wherein the method comprising:
 scanning a white reference original sheet by emitting light from the light source; 
 receiving white reference data outputted from each optical element; 
 generating white basic data of each optical element by averaging the white reference data received from the particular number of adjoining optical elements; 
 storing the white basic data in the storage device; 
 scanning the reference member by emitting light from the light source; 
 receiving reference member data outputted from each optical element; 
 generating fluctuation data of each optical element according to a particular calculation based on the reference member data; and 
 generating the correction data of each optical element by adding the fluctuation data to the white basic data. 
 
 
     
     
       10. The method according to  claim 9 , further comprising:
 generating a white average by averaging the white reference data of all optical elements, 
 wherein the generating fluctuation data includes:
 generating a reference average by averaging the reference member data of all optical elements; 
 generating reference basic data of each optical element by averaging the reference member data of the particular number of adjoining optical elements; and 
 generating reference fluctuation data of each optical element by subtracting the reference basic data from the reference member data; and 
 generating the fluctuation data by multiplying the reference fluctuation data by the white average, and by dividing the multiplication result by the reference average. 
 
 
     
     
       11. The method according to  claim 10 ,
 wherein: 
 the plurality of optical elements is an even number of optical elements; 
 for each optical element arranged between a top pixel position and a center position of the plurality of optical element, the reference basic data is generated by averaging the reference member data of the particular number of adjoining optical elements, the particular number of adjoining optical elements being successively arranged from each optical element toward a last pixel position; and 
 for each optical element arranged between the center position and the last pixel position of the plurality of optical elements, the reference basic data is generated by averaging the reference member data of the particular number of adjoining optical elements, the particular number of adjoining optical elements being successively arranged from each optical element toward the top pixel position. 
 
     
     
       12. The method according to  claim 11 
 wherein: 
 for each optical element arranged between the top pixel position and the center position of the plurality of optical element, the white basic data is generated by averaging the white reference data of the particular number of adjoining optical elements, the particular number of adjoining optical elements being successively arranged from each optical element toward the last pixel position; and 
 for each optical element arranged between the center position and the last pixel position of the plurality of optical elements, the white basic data is generated by averaging the white reference data of the particular number of adjoining optical elements, the particular number of adjoining optical elements being successively arranged from each optical element toward the top pixel position. 
 
     
     
       13. The method according to  claim 10 , further comprising:
 determining a plurality of groups of the optical elements, each group including the particular number of successively adjoining optical elements, 
 wherein the reference basic data of each optical element in each group is generated by averaging the reference member data of the particular number of successively adjoining optical elements in each group. 
 
     
     
       14. The method according to  claim 13 ,
 wherein: 
 a particular group of the optical elements includes a number of optical elements, the particular group being one of the plurality of groups, the number being less than the particular number; and 
 the reference basic data of each optical element in the particular group is generated by averaging the reference member data of the particular number of successively adjoining optical elements, the particular number of successively adjoining optical elements being successively arranged from a last optical element in the particular group toward a top pixel position. 
 
     
     
       15. The method according to  claim 13 ,
 wherein the white basic data of each optical element in each group is generated by averaging the white reference data of the particular number of successively adjoining optical elements in each group. 
 
     
     
       16. The method according to  claim 15 ,
 wherein: 
 a particular group of the optical elements includes a number of optical elements, the particular group being one of the plurality of groups, the number being less than the particular number; and 
 the white basic data of each optical element in the particular group is generated by averaging the white reference data of the particular number of successively adjoining optical elements, the particular number of successively adjoining optical elements being successively arranged from a last optical element in the particular group toward a top pixel position.